NOTES 



ASTRONOMY 



By A. C. D. Crommelix. D.Sc. 



NO\"A LACERTAE. — The visible existence of Nova 

 Lacertae, before its outburst, noted as possible by Mr. 

 Bellamy last month, has now been fully verified. Professor 

 Wolf has measured plates taken in 1904 which give the 

 position (referred to the equinox of 1900) Right Ascension 

 22" 31"" 44"-99 North Declination, 52° ll' 55"-9. His plates 

 of the present year give Right Ascension O^-IO greater, 

 and Declination 0"-l greater. Professor Barnard has also 

 identified the object on plates of his. taUen in 1S93. 1907 and 



1909. He has also measured these plates, finding the position 

 practically identical with that of the present year, thus leaving 

 no doubt of the identity of the object, and showing that its 

 proper motion is small, which we expect to be the case with 

 Novae, from the fact that they always appear in or near the 

 Milky Way, and are. therefore, very remote. The magnitude 

 before the outburst was twelve-and-a-half according to 

 Wolf, fourteen according to Barnard. It would not. 

 therefore, be visible on plates taken with a short exposure, 

 which probably explains its absence on the plates taken 

 at Harvard on November 19th last, and on earlier dates. 

 This is, I believe, the first occasion on which a Nova 

 has been certainly identified with a visible pre-existent 

 object: of course, the probability of doing so increases as the 

 storehouse of plates grows larger. But this is not the only 

 reason, for plates of the Nova Persei region were in existence. 

 and failed to reveal any trace of it. It is evident that that 

 outbreak was on a grander scale than the present one, for it 

 sprang up from the fifteenth magnitude !or fainter) to the first, 

 while this has only risen from the fourteenth to the fifth. It 

 will be interesting to see whether it declines to its former 

 magnitude, or remains permanently brighter. Professor 

 Barnard notes a peculiarity which it shares with Nova 

 Geminorum, viz.. that it has two distinct and sharp foci, 

 one at the ordinary focus, the other eight millimetres further 

 out. and due to the great brilliance of the crimson H (alpha) 

 line of hydrogen. The Nova has been steadily declining 

 since the outburst ; its light fell off during December from 

 the fifth to the seventh magnitvide, and by the end of January 

 it was about eight-and-a-half. Its circumpolar position will 

 enable it to be continuously kept in view during the decline 

 of its light. 



THE SPECTRUM OF MARS.— Astronomers will remember 

 Professor Campbell's expedition to the top of Mount Whitney, 

 in the endeavour to obtain evidence of the presence or otherwise 

 of water-vapour in the atmosphere ot Mars. He has now 

 approached the problem in another manner. It is many years 

 since the shift of lines in the solar spectrum due to rotation 

 was used to distioguish solar lines from those that had their 

 origin in our atmosphere. Great dispersion was necessary, 

 owing to the slowness of the sun's rotation. In the case of 

 Mars, an equal dispersion is unattainable, owing to the 

 faintness of the spectrum, but the relative velocity is much 

 higher. Professor Campbell and Dr. Albrecht, took a series 

 of plates with a specially designed grating-spectroscope in 

 January and February, 1910, using plates rendered sensitive to 

 the red-end, where the water-vapour band is situated. After 

 careful examination of the plates they state that the amount of 

 water-vapour in the planet's atmosphere on February 2nd. 



1910. was certainly less than one-fifth of that in the air above 

 Mount Hamilton at the time. The amount of oxygen in 

 Mars' atmosphere was also relatively small. These results 

 are only what we should expect, for it is obvious, both from 

 the planet's small mass, and from the great distinctness with 

 which the markings are seen, that its atmosphere is very much 

 Hirer than our own. Those who deny the existence of water- 

 vapour in its atmosphere are driven to adopt the conclusion 

 that the polar caps, and the occasional presence of cloud and 

 mist, are due to some other substance, such as carbon dioxide. 



HALLEY'S COMET is still under observation, and is 

 being assiduously followed by Professor Barnard with the fortv- 

 inch Verkes" Refractor. It is now of the fourteenth magnitude, 

 round, 32" in diameter, slightly condensed, but without a 

 visible nucleus. It is considerably further from the Sun than 

 when first photographed in August, 1909, and yet is two 

 magnitudes brighter, showing that the physical brightening at 

 perihelion persists for some time. Professor Bani;-"' ''nt; 

 hopes of keeping it in view till the end of the year ; it ■. 

 be far outside the orbit of Jupiter, which it will cross i;, .>(,i„ 

 next. It will remain invisible for seventy-four years, and will 

 probably be detected in August. 1985. passing perihelion about 

 February, 1986. 



D'ARREST'S COMET was still in view at the end of 

 January, being seen by M. Gonnessiat at Algiers on January 

 22nd. when it was of magnitude fourteen-and-a-half. The 

 Paris Observatory has recently lost by death M. G. Leveau, 

 whose name is especially associated with this comet, from the 

 laborious care with which he has followed its movements ever 

 since 1864; the large perturbations by Jupiter render the work 

 difficult, but nevertheless his predictions have been extremely 

 e.xact, extending even down to the present return. He also 

 constructed tables of the minor planet Vesta, by which its 

 motion can be calculated with greater con\enience and 

 accuracy than by the method formerly employed. 



BOT.AXV. 



By Professor F. Cavers, D.Sc. F.L.S. 



IRON BACTERIA.— Molisch has recently published one 

 of his excellent monographs (Fischer. Jena ; M. 5), the latest 

 production of his prolific pen being an important summary of 

 his own work, continued for eighteen years, as well as that of 

 other investigators, on this interesting group of bacteria. Since 

 the iron bacteria are of practical as well as scientific interest, 

 this monograph ought to be translated into English, in order 

 to attract wider attention among workers in hydraulic and 

 sanitary engineering, as well as in biological science. To the 

 six already-known species of iron bacteria, Molisch adds three 

 more, of which one grows in the stems and lea\es of aquatic 

 plants. He finds that these bacteria can grow quite well in 

 absence of iron, and that they can make use of manganese 

 instead of iron. The iron dissolved in the water is, according 

 to Molisch. merely deposited in the slimy sheaths of the 

 bacterial filaments in the form of carbonate of iron, which 

 becomes oxidised to ferric oxide, and this is apparently not 

 used by the bacteria in their vital processes but simply acts 

 as a protection to the protoplasm — in much the same way as 

 the silica deposits in diatoms and the epidermal cells of 

 grasses, and so on. 



The iron bacteria occur in most bogs, chalybeate springs, 

 stagnant waters, and sometimes in iron water-pipes — in the 

 latter case often plugging up the pipes, besides fouling the 

 water itself; so far, no species have been found in sea- water. 

 These bacteria may be removed by filtration through sand or 

 coke, or by chemical treatment, and in either case Molisch 

 finds that the real cause of the disappearance of the bacteria 

 is the loss of soluble organic substances which are removed 

 by these processes, the absence of the iron itself being a 

 matter of indifference. Various other organisms — certain 

 .Algae. Flagellates, and Infusoria — are capable of fixing iron ; 

 some of these can also fix manganese, and their mode of action 

 appears to be the same as that of the iron bacteria. Molisch 

 also discusses the formation of bog iron, in which the iron 

 bacteria often play an important part : the formation of rust 

 in iron water-pipes, which is probably due primarily to the 

 action of the water itself acting on bare iron surfaces, though 

 here again the iron bacteria may flourish if organic substances 

 are present in addition to soluble iron oxide ; and the thera- 

 peutic use of chalybeate waters, which are often quite useless 

 for medicinal purposes on account of the precipitation of the 

 iron as insoluble ferric hydroxide. 



105 



